It's "more than likely" a fruitfly found in Whangarei on Tuesday entered the country as a larvae in a piece of fruit, the primary industries minister says.

The Queensland fruitfly was caught in a trap in Whangarei, the second of the pests to be found in New Zealand this year, and the fourth in two years.

In Whangarei today biosecurity staff were swarming over the area in the immediate vicinity of the fruitfly find, but there was little activity outside the 200m radius.

One street - Panorama Drive in Parihaka - is the centre of the action with fruit-disposal bins lining the pavement and biosecurity staff scouring properties for any signs of another fly.

Locals were bemused at finding themselves at the centre of another fly-related scandal.

Resident Ron Jefcoate said staff visited him for the first time this morning, and took a particular interest in his guava tree.

"I asked if they wanted me to clean up all the fallen guavas and they said 'No, no, we'll do it for free', so that was handy," he said.

Staff also asked residents not to spray any insecticides, as they can interfere with the trapping system, and wanted to know the last time any fruit had been removed from the area.

The latest discovery, found just 400 metres from where the last fruitfly was found, has sparked calls for the Ministry for Primary Industries (MPI) to review how it manages biosecurity risks.

But Primary Industries Minister Nathan Guy this morning rejected claims biosecurity standards were not up to task.

"What my officials are telling me is that it's very unlikely that this find is related to the previous find because we followed international best practice, we did a whole lot more trapping in the area, we collected fruit, we dissected it to analyse whether there were any eggs or larvae," he said on Firstline.

"We follow through international best practice, we follow through for a couple of weeks.

"If we haven't found any further flies and established that there is no breeding population then we can stand that response down, so it's very important that we follow through on the processes and methodology that we have."

But Opposition MPs are calling on the minister to back up his claims over why he believed the latest incident was separate from the previous find.

Green Party biosecurity spokesman Steffan Browning said a connection between the two most-recent discoveries was likely.

Meanwhile, Guy said investigations were continuing to try to establish how the fruitfly made it into the country.

"It's very hard to establish, because we have multiple pathways," Guy said.

"MPI are investigating and trying to establish how a fruitfly might have got in, but it's more than likely it's come in in a piece of fruit in an egg or larvae state, and then it's gone through the pupae and then it's hatched into a fruitfly and we've caught it in a trap."

An MPI official was in Australia carrying out a "systems audit" on whether the import health standard needed strengthening.

Guy denied there was a fundamental border security problem.

"No, we follow international best practice, we've got 7500 traps up and down the country," he said.

"This shows the system is working. It's a multi-layered biosecurity system."

Labour's primary industries spokesman, Damien O'Connor, labelled the new discovery as a "massive failure" for MPI.

"This fly is the fourth fruitfly to be found in New Zealand and shows a systemic problem which the ministry has been unable to fix," he said.

O'Connor has called for a ban on all fruit imports from high-risk areas until systems were in place to prevent further incursions.

At a cost to the taxpayer of $1 million per fly, it would make sense for the Government to invest more in frontline biosecurity, he said.

Horticulture NZ chief executive Peter Silcock said it was unbelievable the country was faced with another Queensland fruitfly scare.

"We do have to urgently look at how we are managing the biosecurity risk, so we don't keep finding this pest in our traps," he said, adding this was a serious situation for the entire New Zealand horticulture industry and home gardeners.

MPI deputy director general compliance and response, Andrew Coleman said MPI was working closely with international trading partners and the horticulture industry to minimise the risk to New Zealand growers and exporters.

MPI was defining a controlled area around the location of the fruitfly find, and the movement of fruit and vegetables out of this area would be restricted. MPI would provide extensive information about this in the near future and would work closely with the local community.

"The ministry is aware that fruitfly populations have dramatically increased in Australia in recent months and in light of the previous Whangarei find, we have been reviewing our importing requirements for fruitfly risk goods," Coleman said.

Prime Minister John Key said this morning that this latest incursion was not related to the one found earlier in the year. Nevertheless, questions would have to be asked if there was any fault in the system and if there was any reason why two of the insects had been found in the short space of time.

Key said he noticed Horticulture New Zealand, the industry representative body, was not calling for a ban on Australian imports.

"The impact of that would obviously be significant for consumers, so on the one hand they're obviously trying to protect a very important domestic industry and making sure both its domestic sales and export sales are protected," he said.

"But on the other side of the coin consumers would probably be up in arms if there were certain times of the year they couldn't get fruit from overseas."

Key said there was not enough information to say if claims the fly came in on a private yacht that had not been fumigated, were correct.

"But this is now the second one that's taken place in the same area, so the obvious question is why," he said.

"If they're not related, is there some sort of defect or fault or error in the system?

"If it is potentially because of private yachts, then that will be an area we will have to address, but in the short term I think it's determining whether there are any other incursions and the second step is making sure that all the systems are as fail-safe as they can be."

Key said trading partners had not reacted negatively.

"I think they can see that New Zealand takes this seriously, that we have good systems in place," he said.

"They'll be waiting to see whether it's an isolated fruitfly as it was earlier in the year.

"We are very transparent in what we do and that's one of the strengths in our system."